1. Field of the Invention
The present invention relates to the production of N-vinyl pyrrolidone by the catalytic dehydration of N-hydroxyethyl pyrrolidone using an amorphous mixture of metal oxides such as a mixture of calcium and zinc oxides.
2. Description of the Prior Art
It is known to produce N-vinyl pyrrolidone by the catalytic dehydration of N-hydroxyethyl pyrrolidone. U.S. Pat. No. 2,669,570 describes this reaction and suggests that suitable catalysts for the reaction include calcium oxide, aluminum oxide as well as mixtures of aluminum oxide-iron oxide-potassium hydroxide.
U.S. Pat. No. 3,821,245 also describes the reaction and suggests as catalyst an oxide of zirconium, thorium, cerium, zinc and chromium or a mixture of these oxides. The oxide catalysts are sintered at 500-1200° C. prior to use. In Example 14 a zinc oxide catalyst baked at 700° C. for 2 hours is used while in Example 17 a mixture of zinc oxide and chromium oxide also baked at 700° C. for 2 hours was used.
U.S. Pat. No. 5,569,770 shows the reaction using a mixed oxide of Group IV elements or an oxide of Group IV elements modified by Group I or Group II elements. High temperature calcination of the catalyst is taught.